Intestinal enteroids recapitulate the effects of short-chain fatty acids on the intestinal epithelium.

Abstract

Enteroids are cultured primary intestinal epithelial cells that recapitulate epithelial lineage development allowing for a more complex and physiologically relevant model for scientific study. The large presence of intestinal stem cells (ISC) in these enteroids allows for the study of metabolite effects on cellular processes and resulting progeny cells. Short-chain fatty acids (SCFA) such as butyrate (BUT) are bacterial metabolites produced in the gastrointestinal tract that are considered to be beneficial to host cells. Therefore, the objective was to study the effects of SCFAs on biomarkers of ISC activity, differentiation, barrier function and epithelial defense in the intestine using mouse and human enteroid models. Enteroids were treated with two concentrations of acetate (ACET), propionate (PROP), or BUT for 24 h. Enteroids treated with BUT or PROP showed a decrease in proliferation via EdU uptake relative to the controls in both mouse and human models. Gene expression of Lgr5 was shown to decrease with BUT and PROP treatments, but increased with ACET. As a result of BUT and PROP treatments, there was an increase in differentiation markers for enterocyte, Paneth, goblet, and enteroendocrine cells. Gene expression of antimicrobial proteins Reg3β, Reg3γ, and Defb1 were stimulated by BUT and PROP, but not by ACET which had a greater effect on expression of tight junction genes Cldn3 and Ocln in 3D enteroids. Similar results were obtained with human enteroids treated with 10 mM SCFAs and grown in either 3D or Transwell™ model cultures, although tight junctions were influenced by BUT and PROP, but not ACET in monolayer format. Furthermore, BUT and PROP treatments increased transepithelial electrical resistance after 24 h compared to ACET or control. Overall, individual SCFAs are potent stimulators of cellular gene expression, however, PROP and especially BUT show great efficacy for driving cell differentiation and gene expression.